Error code E99 occurs when you use your Xbox 360 console.

Problem

You may see the following error message and code when you use your Xbox 360 console:

System Error: Contact Xbox Customer Support

Error code E99

This means there may be a problem with the console.

Solutions

Try the following steps:

Xbox 360 E console or Xbox 360 S console

Disconnect and reconnect all accessories. If the power button light is red after reconnecting a specific accessory, it indicates that the accessory is faulty and should be replaced. If the power supply light remains green after you have reconnected all accessories, your issue may have been a loose accessory connection.

Remove the hard drive. If the system error message is not displayed with the hard drive removed, your hard drive may be experiencing a hardware failure. Order a new Xbox 360 Hard Drive from our Xbox Online Service Center (sign in with your Microsoft account). Console registration is required to replace a hard drive under warranty.

Remove any USB flash drives.

If this step resolves the problem, reattach the USB flash drive to make sure the error occurs only when it is connected. If this is true, use another USB flash drive.